/Engine/Plugins/Runtime/GeometryProcessing/Source/DynamicMesh/Public/GroupTopology.h
Set of vertex ID's that are currently considered corners despite not originally having 3 or more attached group edges (due to the effects of ShouldAddExtraCornerAtVert or RebuildTopologyWithSpecificExtraCorners).
const [TSet](API\Runtime\Core\Containers\TSet)< int32 > & GetCurrentExtraCornerVids() const